The present invention generally relates to an apparatus and method for forming an image, and is capable of being applied to an image forming apparatus and method, which utilize toner of a copying machine or printer having a photosensitive drum.
In an image forming apparatus and method utilizing toner, there is carried out an image forming process for electrifying minus charges on the surface of a photosensitive drum, exposing (varying the surface potential of) the photosensitive drum to laser beams based on picture signals to form a latent image, causing the photosensitive drum to absorb minus charged toner to form a visible image, and transferring and fixing the visible image on a paper.
In such image formation, a toner (which will be hereinafter referred to as a xe2x80x9crecovered tonerxe2x80x9d) which has been already utilized in image formation, and a toner (which will be hereinafter referred to as a xe2x80x9cnew tonerxe2x80x9d) which has not yet been utilized in image formation, are mixed to be utilized. That is, the recovered toner is recycled to be used.
Conventionally, as a method for recycling a recovered toner, there is a method for conveying a recovered toner, which leaves a cleaner auger, to a developing device by means of a connecting auger, which connects the cleaner auger to the developing device, and returning the recovered toner directly into the developing device. In this method, the rotation of the cleaner auger must be in synchronism with the rotation of the photosensitive drum, and the rotation of the connecting auger to the developing device must be connected with the cleaner auger.
If a toner specific concentration sensor provided in the developing device is utilized for carrying out a toner empty display, which is carried out when the new toner is completely consumed, and/or for carrying out the stop of an image forming operation due to toner empty when the developer toner specific concentration decreases to a predetermined toner specific concentration, even if the new toner is completely consumed in a cartridge or hopper, the supply of toner recovered from the cleaner part continues, so that the percentage of the recovered toner in the developing device increases.
An external additive is peeled from the recovered toner, and paper powder is mixed in the recovered toner. Therefore, even if the recovered toner is supplied into the developing device, the rise of the quantity of electrification is worse than that in the case of the new toner. For that reason, the percentage of the recovered toner increases to be larger than the usual percentage, so that image fogging tends to occur.
It is an object of the present invention to prevent an image having image fogging from being formed when a new toner is completely consumed in a cartridge or hopper.
In order to accomplish the aforementioned object, according to the present invention, an image forming apparatus comprises: recovered toner housing means for temporarily storing therein a recovered toner; a connecting/conveying device for conveying the recovered toner from a cleaner part to the recovered toner housing means; recovered toner supply means for supplying the recovered toner, which is housed in the recovered toner housing means, to a developing device; new toner housing means for housing therein a new toner; new toner supply means for supplying the new toner, which is stored in the new toner housing means, to the developing device; no-residual-amount detecting means for detecting no residual amount of the new toner in the new toner housing means; and control means for separately controlling the recovered toner supply means and the new toner supply means, to cause the recovered toner or the new toner to be supplied to the developing device, wherein the control means restricts the supply of the recovered toner from the recovered toner housing means to the developing device when the no-residual-amount detecting means detects no residual amount of the new toner.
In order to accomplish the aforementioned object, according to the present invention, there is provided an image forming method for causing a connecting/conveying device to convey a recovered toner from a cleaner part to the recovered toner housing means to house therein the recovered toner, and causing control means to separately control the recovered toner supply means and the new toner supply means to supply the recovered toner, which is stored in the recovered toner housing means, and/or a new toner, which is stored in the new toner housing means, to the developing device, wherein the control means restricts the supply of the recovered toner from the recovered toner housing means to the developing device when the no-residual-amount detecting means detects no residual amount of the new toner in the new toner housing means.